U.S. patent application number 13/341686 was filed with the patent office on 2013-05-23 for wireless communication device capable of efficient radio access technology measurements.
This patent application is currently assigned to Broadcom Corporation. The applicant listed for this patent is C. Ashok Kumar Reddy, Shashidhar Vummintala. Invention is credited to C. Ashok Kumar Reddy, Shashidhar Vummintala.
Application Number | 20130130687 13/341686 |
Document ID | / |
Family ID | 46796233 |
Filed Date | 2013-05-23 |
United States Patent
Application |
20130130687 |
Kind Code |
A1 |
Kumar Reddy; C. Ashok ; et
al. |
May 23, 2013 |
WIRELESS COMMUNICATION DEVICE CAPABLE OF EFFICIENT RADIO ACCESS
TECHNOLOGY MEASUREMENTS
Abstract
A wireless communication device is disclosed that is capable of
performing efficient measurements of secondary radio access
technologies (RATs). The device includes multiple receiver chains.
While operating in a first RAT, the device receives a measurement
gap in order to perform measurements. Even though the measurement
gap may be too small to adequately measure the other RAT, the
device controls one of the receiver chains to measure the other RAT
during a time period that overlaps with the measurement gap. In
addition, when preparing for an inter-RAT handoff, the device
controls one of the receiver chains to perform measurements
regardless of whether a measurement gap has been received. In this
manner, measurements of alternative RATs are efficiently performed,
and handoff latency is significantly reduced.
Inventors: |
Kumar Reddy; C. Ashok;
(Bangalore, IN) ; Vummintala; Shashidhar;
(Bangalore, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kumar Reddy; C. Ashok
Vummintala; Shashidhar |
Bangalore
Bangalore |
|
IN
IN |
|
|
Assignee: |
Broadcom Corporation
Irvine
CA
|
Family ID: |
46796233 |
Appl. No.: |
13/341686 |
Filed: |
December 30, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61562196 |
Nov 21, 2011 |
|
|
|
Current U.S.
Class: |
455/436 ;
455/67.11 |
Current CPC
Class: |
H04W 36/08 20130101;
Y02D 30/70 20200801; Y02D 70/126 20180101 |
Class at
Publication: |
455/436 ;
455/67.11 |
International
Class: |
H04W 24/00 20090101
H04W024/00; H04W 36/30 20090101 H04W036/30 |
Claims
1. A wireless communication device, comprising: a first
communication module configured to communicate with another
wireless communication device using a first RAT (radio access
technology); a second communication module configured to perform
measurement of a second RAT, wherein the first communication module
is configured to maintain a first RAT communication link with the
other wireless communication device during the measurement of the
second RAT.
2. The wireless communication device of claim 1, wherein the second
communication module is configured to perform the measurement of
the second RAT during a measurement gap associated with the first
RAT.
3. The wireless communication device of claim 2, wherein the second
communication module is configured to begin the measurement before
the measurement gap, and end the measurement after the measurement
gap.
4. The wireless communication device of claim 2, wherein the second
communication module is configured to begin the measurement during
the measurement gap, and end the measurement after the measurement
gap.
5. The wireless communication device of claim 2, wherein the second
communication module is configured to begin the measurement before
the measurement gap, and end the measurement during the measurement
gap.
6. The wireless communication device of claim 1, further comprising
a controller module configured to set a priority of the
measurement.
7. The wireless communication device of claim 6, wherein the second
communication module is configured to perform the measurement of
the second RAT during a measurement gap associated with the first
RAT when the controller module sets the measurement as normal
priority.
8. The wireless communication device of claim 7, wherein the second
communication module performs the measurement of the second RAT
regardless of whether the measurement gap exists for the first RAT
when the controller module sets the measurement as high
priority.
9. The wireless communication device of claim 8, wherein the
controller module is configured to set the priority of the
measurement as high-priority when the measurement is to be
performed in anticipation of a handoff.
10. A wireless communication device, comprising: a first
communication module configured to communicate using a first RAT,
and to perform a measurement of a second RAT; a second
communication module configured to communicate using the first RAT,
and to also perform the measurement of the second RAT; and a
measurement module configured to select one of the first
communication module or the second communication module to perform
the measurement of the second RAT.
11. The wireless communication device of claim 10, wherein the
measurement module is configured to switch between selecting the
first communication module and selecting the second communication
module with a predetermined periodicity.
12. The wireless communication device of claim 10, wherein the
measurement module is configured to select the first communication
module to perform the measurement when a most recent previous
measurement was performed by the second communication module, and
is configured to select the second communication module to perform
the measurement when the most recent previous measurement was
performed by the first communication module.
13. The wireless communication device of claim 10, wherein the
measurement module is configured to randomly select one of the
first communication module or the second communication module to
perform the measurement.
14. The wireless communication device of claim 10, further
comprising a controller module configured to determine which of the
first communication module or the second communication module has
poorer first-RAT communication, and wherein the measurement module
is configured to select the communication module determined by the
controller module to have the poorer first-RAT communication.
15. A method for performing a measurement of a second RAT (radio
access technology) in a wireless communication device currently
communicating using a first RAT, the method comprising: determining
a priority of a measurement to be performed of the second RAT; and
performing the measurement of the second RAT.
16. The method of claim 15, further comprising receiving a
measurement gap, wherein the performing of the measurement overlaps
with the measurement gap.
17. The method of claim 16, wherein the performing of the
measurement begins before the measurement gap, and ends after the
measurement gap.
18. The method of claim 16, wherein the performing of the
measurement begins before the measurement gap, and ends during the
measurement gap.
19. The method of claim 16, wherein the performing of the
measurement begins during the measurement gap, and ends after the
measurement gap.
20. The method of claim 15, wherein if the measurement is
determined to be high-priority, then the performing of the
measurement occurs immediately, and wherein if the measurement is
determined not to be high-priority, then the performing of the
measurement overlaps with a measurement gap.
Description
CROSS-REFERENCED TO RELATED APPLICATIONS
[0001] This patent application claims the benefit of U.S.
Provisional Patent Application No. 61/562,196, filed Nov. 21, 2011,
entitled "Fourth Generation (4G) Communication System," which is
incorporated herein by reference in its entirety.
BACKGROUND
[0002] 1. Field of Invention
[0003] The invention relates to wireless communications, and more
specifically to a wireless communication device that is capable of
efficiently measuring a secondary radio access technology.
[0004] 2. Related Art
[0005] Wireless communication devices, such as cellular telephones
to provide an example, are becoming commonplace in both personal
and commercial settings. The wireless communication devices provide
users with access to all kinds of information, as well as the
ability to communicate with other such devices across large
distances. For example, a user can access the internet through an
internet browser on the device, download miniature applications
(e.g., "apps") from a digital marketplace, send and receive emails,
or make telephone calls using a voice over internet protocol
(VoIP). Consequently, wireless communication devices provide users
with significant mobility, while allowing them to remain
"connected" to communication channels and information.
[0006] Wireless communication devices communicate with one or more
other wireless communication devices or wireless access points to
send and receive data. Typically, a first wireless communication
device generates and transmits a radio frequency signal modulated
with encoded information. This radio frequency signal is
transmitted into a wireless environment and is received by a second
wireless communication device. The second wireless communication
device demodulates and decodes the received signal to obtain the
information. The second wireless communication device may then
respond in a similar manner. The wireless communication devices can
communicate with each other or with access points using any
well-known modulation scheme, including simple amplitude modulation
(AM), simple frequency modulation (FM), quadrature amplitude
modulation (QAM), phase shift keying (PSK), quadrature phase shift
keying (QPSK), and/or orthogonal frequency-division multiplexing
(OFDM), as well as any other communication scheme that is now, or
will be, known.
[0007] Different wireless communication devices may communicate
using any one of different radio access technologies (RATs),
including WiMAX, LTE, 4G, 3G, 2G, and WiFi, among others. Some
devices are capable of communicating using multiple different RATs.
At any given time, a multi-RAT device can be currently
communicating using a primary RAT, while measuring signals from one
or more secondary RATs that the device is not currently utilizing,
but may utilize in the future if conditions warrant. The
measurements for the secondary RAT occur only during time periods
allocated for measurement gaps that are provided by the primary
RAT.
[0008] As a result of this measurement scheme, the performance of
current devices suffers. Specifically, measurement gaps provided
for the primary RAT may be insufficient to measure the secondary
RATs. For example, 2G measurement gaps are approximately 4.6ms.
However, 4G measurements typically require 5-6 ms. As a result, in
order to perform the 4G measurement, current devices must ignore
several of the incoming 2G packets that follow the 2G measurement
gap in order to complete the 4G measurement. This can result in
erroneous signals and/or reduced throughput through retransmission
of the ignored signal.
[0009] In addition, when performing a handoff from the primary RAT
to a secondary RAT, typical devices must again acquire the
measurements from the secondary RAT. This handoff measurement is
performed after communications with the primary RAT have ceased,
which significantly adds to handoff preparation time, and therefore
increases handoff latency.
[0010] Consequently, there is a need for a wireless communication
device capable of efficiently performing measurements of secondary
RATs. Further aspects and advantages of the invention will become
apparent from the detailed description that follows.
BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES
[0011] Embodiments of the invention are described with reference to
the accompanying drawings. In the drawings, like reference numbers
indicate identical or functionally similar elements. Additionally,
the left most digit(s) of a reference number identifies the drawing
in which the reference number first appears.
[0012] FIG. 1 illustrates a block diagram of a wireless
communication environment according to an exemplary embodiment of
the invention;
[0013] FIG. 2 illustrates a block diagram of a wireless
communication device that is implemented as part of the wireless
communication environment according to an exemplary embodiment of
the invention;
[0014] FIG. 3A illustrates a measurement timing configuration that
may be implemented by the wireless communication device according
to an exemplary embodiment of the invention;
[0015] FIG. 3B illustrates a measurement timing configuration that
may be implemented by the wireless communication device according
to an exemplary embodiment of the invention;
[0016] FIG. 4 illustrates a block diagram of a method for
performing a measurement of a secondary RAT within a wireless
communication device according to an exemplary embodiment of the
invention.
[0017] The invention will now be described with reference to the
accompanying drawings. In the drawings, like reference numbers
generally indicate identical, functionally similar, and/or
structurally similar elements. The drawing in which an element
first appears is indicated by the leftmost digit(s) in the
reference number.
DETAILED DESCRIPTION OF THE INVENTION
[0018] The following Detailed Description refers to accompanying
drawings to illustrate exemplary embodiments consistent with the
invention. References in the Detailed Description to "one exemplary
embodiment," "an exemplary embodiment," "an example exemplary
embodiment," etc., indicate that the exemplary embodiment described
may include a particular feature, structure, or characteristic, but
every exemplary embodiment may not necessarily include the
particular feature, structure, or characteristic. Moreover, such
phrases are not necessarily referring to the same exemplary
embodiment. Further, when a particular feature, structure, or
characteristic is described in connection with an exemplary
embodiment, it is within the knowledge of those skilled in the
relevant art(s) to affect such feature, structure, or
characteristic in connection with other exemplary embodiments
whether or not explicitly described.
[0019] The exemplary embodiments described herein are provided for
illustrative purposes, and are not limiting. Other exemplary
embodiments are possible, and modifications may be made to the
exemplary embodiments within the spirit and scope of the invention.
Therefore, the Detailed Description is not meant to limit the
invention. Rather, the scope of the invention is defined only in
accordance with the following claims and their equivalents.
[0020] Embodiments of the invention may be implemented in hardware
(e.g., circuits), firmware, software, or any combination thereof.
Embodiments of the invention may also be implemented as
instructions stored on a machine-readable medium, which may be read
and executed by one or more processors. A machine-readable medium
may include any mechanism for storing or transmitting information
in a form readable by a machine (e.g., a computing device). For
example, a machine-readable medium may include read only memory
(ROM); random access memory (RAM); magnetic disk storage media;
optical storage media; flash memory devices; electrical, optical,
acoustical or other forms of propagated signals (e.g., carrier
waves, infrared signals, digital signals, etc.), and others.
Further, firmware, software, routines, instructions may be
described herein as performing certain actions. However, it should
be appreciated that such descriptions are merely for convenience
and that such actions in fact results from computing devices,
processors, controllers, or other devices executing the firmware,
software, routines, instructions, etc.
[0021] The following Detailed Description of the exemplary
embodiments will so fully reveal the general nature of the
invention that others can, by applying knowledge of those skilled
in relevant art(s), readily modify and/or adapt for various
applications such exemplary embodiments, without undue
experimentation, without departing from the spirit and scope of the
invention. Therefore, such adaptations and modifications are
intended to be within the meaning and plurality of equivalents of
the exemplary embodiments based upon the teaching and guidance
presented herein. It is to be understood that the phraseology or
terminology herein is for the purpose of description and not of
limitation, such that the terminology or phraseology of the present
specification is to be interpreted by those skilled in relevant
art(s) in light of the teachings herein.
[0022] Although the description of the present invention is to be
described in terms of wireless communication (specifically cellular
communication), those skilled in the relevant art(s) will recognize
that the present invention may be applicable to other
communications that use wired or other wireless communication
methods without departing from the spirit and scope of the present
invention.
AN EXEMPLARY WIRELESS COMMUNICATIONS ENVIRONMENT
[0023] FIG. 1 illustrates a block diagram of a wireless
communication environment 100 according to an exemplary embodiment
of the invention. The wireless communication environment 100
provides wireless communication of information, such as one or more
commands and/or data, between wireless communication devices. The
wireless communication devices may each be implemented as a
standalone or a discrete device, such as a mobile telephone, or may
be incorporated within or coupled to another electrical device or
host device, such as a portable computing device, a camera, or a
Global Positioning System (GPS) unit or another computing device
such as a personal digital assistant, a video gaming device, a
laptop, a desktop computer, or a tablet, a computer peripheral such
as a printer or a portable audio and/or video player to provide
some examples and/or any other suitable electronic device that will
be apparent to those skilled in the relevant art(s) without
departing from the spirit and scope of the invention.
[0024] The exemplary wireless communication environment 100
includes a first wireless communication device 110 and a second
wireless communication device 150. The first wireless communication
device 110 may represent an exemplary embodiment of a user
equipment and the second wireless communication device 150 may
represent an exemplary embodiment of a second user equipment or a
base station within a cellular communications network.
[0025] The first wireless communication device 110 transmits a
first wireless signal 115 toward the second wireless communication
device 150 using any acceptable modulation scheme. The second
wireless communication device 150 receives the first wireless
signal 115. The second wireless communication device 150 processes
the received first communication signal and, if necessary,
transmits a second wireless signal 155 back to the first wireless
communication device 110. In this manner, the first wireless
communication device 110 and the second wireless communication
device 150 exchange information ("communicate") with one
another.
AN EXEMPLARY WIRELESS COMMUNICATION DEVICE
[0026] FIG. 2 illustrates a block diagram of a wireless
communication device 200 that is implemented as part of the
wireless communication environment 100 according to an exemplary
embodiment of the invention. The wireless communication device 200
includes a first communication module 210 and a second
communication module 220, and may represent an exemplary embodiment
of the first wireless communication device 110 or the second
wireless communication device 150.
[0027] The wireless communication device 200 includes a controller
module 230 that performs most of the functions within the wireless
communication device 200, including background processing, signal
processing, and control. The controller module 230 is connected to
each of the first communication module 210 and the second
communication module 220. The first communication module 210
receives signals from, and transmits signals to, the wireless
communication environment 100 via an antenna 201. The first
communication module 210 may include a first receiver chain for
individually receiving and front-end processing signals. The second
communication module 220 receives signals from, and transmits
signals to, the wireless communication environment 100 via an
antenna 202. The second communication module 220 may include a
second receiver chain for individually receiving and front-end
processing signals.
[0028] Upon receipt of signals from the wireless communication
environment 100, the first communication module 210 and the second
communication module 220 perform front-end processing on the
received signals and forward the received signals to the controller
module 230. The front-end processing may include down-conversion,
demodulation and decoding, among other processings. The controller
module 230 may also control the operation of, and generate signals
for transmission by, one or more of the first communication module
210 and the second communication module 220.
[0029] Depending on the current RAT, the wireless communication
device may use one or both of the first communication module 210
and the second communication module 220 for communication. For
example, a typical 4G communication requires at least two antennas
and receive chains, whereas a typical 2G communication requires the
use of only a single antenna/receive chain. Accordingly, when
communicating in 4G, the controller module 230 controls both the
first communication module 210 and the second communication module
220 to receive signals from the wireless communication environment
100. Alternatively, when communicating in 2G, the controller module
230 controls only the first communication module 210 to receive
signals from the wireless communication environment 100.
[0030] During communication, it is necessary to perform
measurements on both the current RAT and on secondary (alternative)
RATs. From the measurements, the wireless communication device 200
is able to optimize communication by either adjusting
modulation/coding schemes on the current RAT, or by initiating a
handover to an alternative RAT. In order to control the
measurements by the first communication module 210 and/or the
second communication module 220, the wireless communication device
200 further includes a measurement module 240. The measurement
module 240 receives commands from the controller module 230
regarding whether to initiate a measurement, and may be capable of
requesting and detecting measurement gaps, as will be discussed in
further detail below.
EXEMPLARY DEVICE CONFIGURATIONS FOR MEASURING ALTERNATIVE RADIO
ACCESS TECHNOLOGIES
Measure Overlapping with Measurement Gap
[0031] FIG. 3A illustrates a measurement timing configuration that
may be implemented by the wireless communication device 200
according to an exemplary embodiment of the invention.
[0032] As discussed above, devices that are capable of
communicating over multiple RATs suffer performance complications
when attempting to perform measurements on a RAT whose measurement
time exceeds the allocated measurement gap time for the current
RAT. This typically occurs when communicating on a single-antenna
RAT, such as 2G.
[0033] FIG. 3A shows a communication. timing 300A for the first
communication module 210 and a measurement timing 300B for the
second communication module 220 on which a measurement 325 is to be
performed for the alternative RAT. Each of the first communication
module 210 and the second communication module 220 may be capable
of communicating using the same or different RATs. The
communication timing 300A includes a communication link 305 with
another wireless communication device, and implements a measurement
gap 310 in between data transfers. As shown in FIG. 3A, the
duration of the measurement 325 (time t1-t4) exceeds the amount of
time allocated for the measurement gap 310 (time t2-t3) for the
current RAT.
[0034] In this scenario, the controller module 230 instructs the
measurement module 240 to perform a measurement. After receiving
the measurement instruction from the controller module 230, the
measurement module 240 causes the first communication module 210
and/or the second communication module 220 to request a measurement
gap from the wireless communication device with which the wireless
communication device 200 is currently communicating (e.g. a base
station). The communication module that makes the request for the
measurement gap 310 is preferably the communication module
communicating on the current RAT.
[0035] At time t0, the first communication module 210 is
communicating with another wireless communication device using the
current RAT. In anticipation of the approaching measurement gap
310, and because the current RAT only requires a single
communication module for operation, the measurement module 240
controls the second communication module 220 to begin performing
its measurement 325 of the secondary RAT at time t1. At time t2,
the first communication module 210 ends data communication, and
begins the measurement gap 310. The measurement gap 310 ends at
time t3, at which time the first communication module 210 resumes
data communication. At time t4, the measurement 325 concludes.
[0036] It should be understood that the measurement 325 can
encompass one or more of measuring channel conditions of the
measured RAT (such as CINR, RSSI, etc.), and acquiring system
information of the measured RAT (such as time offset, system frame
number, etc.). However, when performed during a measurement gap (as
in FIG. 3A), the measurement 325 typically will be used for
measuring channel conditions.
[0037] This measurement timing configuration provides numerous
advantages over current related art devices. Specifically, the
measurement module 240 causes the measurement 325 to be performed
by only one of the communication modules, namely the communications
module that is unused by current RAT. In this manner, communication
on the current RAT proceeds uninterrupted, and without discarding
communication data to perform the measurement for secondary RAT. In
other words, even though the measurement 325 exceeds the
measurement gap 310 in duration, it is not necessary to sacrifice
data to perform the measurement 325. In addition, by scheduling the
measurement 325 to at least overlap with the measurement gap 325,
the negative effects on the current communication by the
measurement 325 are minimized. Specifically, performing the
measurement 325 while attempting to also communicate over the
current RAT can inject undesired noise and interference into the
signals received on the current RAT. By overlapping with the
measurement gap, the injected noise and interference is
significantly reduced.
[0038] Those skilled in the relevant art(s) will recognize that
many modifications may be available to the wireless communication
device 200 and/or the measurement timing configuration within the
spirit and scope of the present invention. For example, the
measurement 325 may be scheduled to start at the beginning of the
measurement gap 305 (time t2) rather than in anticipation of the
measurement gap 305 (time t1), or may be schedule so as to only
partially overlap with the measurement gap 305 depending on the
application.
Measure Outside Measurement Gap
[0039] FIG. 3B illustrates a measurement timing configuration that
may be implemented by the wireless communication device 200
according to an exemplary embodiment of the invention.
[0040] As discussed above, measurements of the alternative RAT
should typically be performed during a measurement gap in order to
avoid injecting undesired amounts of noise and interference into
current RAT incoming signals. However, under certain circumstances,
it may be desirable to perform a measurement 325 regardless of
whether a measurement gap has been received.
[0041] One such scenario is in preparation for handing over to a
secondary RAT. Specifically, after performing certain analyses of
the current RAT and the secondary RAT, the controller module 230 of
the wireless communication device 200 may determine that
communication should be handed over from the current RAT to the
secondary RAT. This typically occurs when conditions on the
secondary RAT exceed those on the current RAT such that handing off
will enhance communication quality.
[0042] Once the decision has been made to hand off to the secondary
RAT, the controller module 230 instructs the measurement module 240
to perform a measurement 325. The controller module 230 also
identifies the measurement 325 as being "high priority." This may
be performed simply by setting a priority flag within a control
signal to the measurement module, or by any other means that is now
or will be known.
[0043] After receiving the instruction to perform the high-priority
measurement, the measurement module 240 does not request or wait
for a measurement gap, but rather causes the second communication
module 220 to immediately (or with minimal delay) perform the
measurement of the secondary RAT, as illustrated in FIG. 3B.
[0044] FIG. 3B shows that, at time t0, the first communication
module 210 is communicating over the current RAT. At, or slightly
prior to time t1, the measurement module 240 receives the
instruction to perform the high-priority measurement 325. At time
t1, the measurement module 240 causes the second communication
module 220 to perform the measurement 325 regardless of whether
first communication module 210 has received a measurement gap. The
measurement module 240 preferably causes the measurement 325 to be
performed with minimal delay from the time the measurement
instruction is received. At time t2, the measurement 325 concludes.
Presuming that the high-priority measurement was requested in
anticipation of an inter-RAT handoff, at a later time t3, the
controller module 230 initiates the handoff and at time t4, the
communication 310 on the current RAT concludes. At this time,
communication on the alternative RAT can begin.
[0045] As discussed above, it should be understood that the
measurement 325 can encompass one or more of measuring channel
conditions of the measured RAT (such as CINR, RSSI, etc.), and
acquiring system information of the measured RAT (such as time
offset, system frame number, etc.). However, when performed in
preparation of a handoff (as in FIG. 3B), the measurement 325
typically will be used for obtaining system information of the
target RAT.
[0046] This measurement configuration also has many advantages over
current related art devices. Specifically, in typical devices, all
measurements for a handoff must be made after conclusion of
communication on the current RAT. This significantly increases
handoff latency, as the measurement 325 would not have begun until
time t4 in the timeline shown in FIG. 3B. By performing the
measurement 325 during the communication 310 on the current RAT,
handoff latency can be significantly reduced. In addition, because
the high-priority measurement 325 is performed in anticipation of a
handoff, the controller module 230 has already determined that the
conditions on the current RAT are undesirable. As a result, any
noise injected by performing the measurement 325 during the
communication 310 is unlikely to have a substantial impact on
current communication. In other words, the current RAT is
presumably already noisy, and the injection of additional noise is
unlikely to have a significant effect on signal quality.
[0047] In addition to the possible injection of noise into the
current RAT, there is a possibility that measurements taken outside
the measurement gap will be underestimated either because the
current RAT radio is ON and/or because the current RAT is
transmitting signals while the new RAT is being measured. However,
this underestimation can be accurately compensated by
characterizing the impact of the leakages as part of the initial
calibration.
[0048] Those skilled in the relevant art(s) will recognize that
many modifications may be available to the above measurement timing
configuration within the spirit and scope of the present invention.
For example, the measurement module 240 may wait a predetermined
period of time for a measurement gap before performing the
high-priority measurement 325. Alternatively, the high-priority
measurement 325 may be performed so as to overlap with the
conclusion of the communication on the current RAT. This
configuration still reduces handover latency, but to a lesser
extent, and further reduces negative effects caused by performing
the measurement during current RAT communications.
Choosing Communication Chain to Perform Measurement
[0049] As discussed above, when the controller module 230
determines that a measurement of an alternative RAT is needed, the
controller module 230 instructs the measurement module 240
accordingly. The measurement module 240 then controls one of the
first communication module 210 or the second communication module
220 to perform the measurement. However, while one of the first
communication module 210 and the second communication module 220
performs the measurement, the other maintains communication on the
current RAT. Consequently, the wireless communication device 200
must select the communication module that will perform the
measurement, which is discussed in detail below.
[0050] In a first configuration, when a measurement is to be taken,
the measurement module 240 causes the first communication module
210 and the second communication module 220 to alternate measuring
the alternative RAT with a predetermined periodicity. For example,
the first communication module 210 and the second communication
module 220 may switch measurement responsibilities within a single
measurement, on a measurement-by-measurement basis, or after a
predetermined number of measurements. In this manner, the wireless
communication device 200 is capable of receiving measurements from
each of the first communication module 210 and the second
communication module 220 for higher measurement accuracy.
[0051] In a second configuration, the controller module 230
maintains communication characteristics of the first communication
module 210 and the second communication module 220 with respect to
the current RAT. For example, the controller module 230 may track
communication quality of the first communication module 210 and the
second communication module 220 with respect to the current RAT.
The communication quality may be measured based on various
characteristics of the communication modules, including SINR
(signal to interference-plus-noise ratio), CINR (carrier to
interference-plus-noise ratio), or RSSI (received signal strength
indication) of received signals, as well as any other signal
strength determination method that is now or will be known. At the
time of the measurement, the controller module 230 also indicates
to the measurement module 240 the communication module having the
best current-RAT characteristics. The measurement module 240 then
controls the stronger communication module to maintain
communication on the current RAT, and controls the weaker
communication module to perform the measurement.
[0052] For example, the controller module 230 may determine that
the first communication module 210 has stronger current-RAT
communication characteristics than the second communication module
220. The controller module 230 then instructs the measurement
module 240 to perform a measurement, and informs the measurement
module 240 that the first communication module 210 has the stronger
current-RAT communication characteristics. The measurement module
240 then controls the second communication module 220 to perform
the desired measurement of the alternative RAT, while controlling
the first communication module 210 to continue current-RAT
communication.
[0053] With this configuration, the wireless communication device
200 maintains its strongest current-RAT communication link. As a
result, the measurement minimally affects current communications by
the wireless communication device 200.
[0054] Those skilled in the relevant art(s) will recognize that
many modifications may be made to the above configurations, and
that alternative configurations may be available within the spirit
and scope of the present invention. For example, the measurement
module 240 can randomly select the communication module to perform
the measurement. In addition, those skilled in the relevant art(s)
will understand that the above configurations can be expanded to
more than two communication modules, and can be used together in
the same wireless communication device.
AN EXEMPLARY METHOD FOR PERFORMING A MEASUREMENT OF AN ALTERNATIVE
RADIO ACCESS TECHNOLOGY IN A WIRELESS COMMUNICATION DEVICE
[0055] FIG. 4 illustrates a block diagram of a method for
performing a measurement of an alternative RAT (a RAT not currently
used for communication) in a wireless communication device. The
wireless communication device preferably includes at least a first
communication module and a second communication module.
[0056] The method begins at step 410, where the wireless
communication device initiates a measurement of the alternative
RAT. The method then proceeds to step 420. In step 420, the
wireless communication device determines whether the measurement is
a high-priority measurement.
[0057] If the measurement is not high-priority, the method proceeds
to step 430. In step 430, the wireless communication device
determines whether a measurement gap has been received. If no
measurement gap has been received, the method returns to step 430.
If a measurement gap has been received, the method proceeds to step
440. In step 440, the wireless communication device performs a
measurement of the alternative RAT using at least one of the first
communication module and the second communication module during a
period of time that overlaps with the measurement gap. The method
then proceeds to step 460, where the method ends.
[0058] Alternatively, if the measurement is high-priority, the
method proceeds to step 430. In step 430, the wireless
communication device performs the measurement of the alternative
RAT immediately (with minimal delay), and without waiting for a
measurement gap. The method then proceeds to step 460, where the
method ends.
[0059] Those skilled in the relevant art(s) will recognize that the
method can additionally or alternatively include any of the
functionality of the wireless communication device 200 discussed
above, and the above description of the exemplary method should
neither be construed to limit the method nor the description of the
wireless communication device 200.
CONCLUSION
[0060] It is to be appreciated that the Detailed Description
section, and not the Abstract section, is intended to be used to
interpret the claims. The Abstract section may set forth one or
more, but not all exemplary embodiments, of the invention, and
thus, are not intended to limit the invention and the appended
claims in any way.
[0061] The invention has been described above with the aid of
functional building blocks illustrating the implementation of
specified functions and relationships thereof. The boundaries of
these functional building blocks have been arbitrarily defined
herein for the convenience of the description. Alternate boundaries
may be defined so long as the specified functions and relationships
thereof are appropriately performed.
[0062] It will be apparent to those skilled in the relevant art(s)
that various changes in form and detail can be made therein without
departing from the spirit and scope of the invention. Thus the
invention should not be limited by any of the above-described
exemplary embodiments, but should be defined only in accordance
with the following claims and their equivalents.
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